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With so few moving parts, one would have thought they'd be more efficient than a reciprocating engine. Why weren't they?
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There are various reasons for lower efficiency, one is that the combustion chamber in a rotary engine needs to be shaped to allow the rotor to move freely. This prevents the shape being optimised for efficient combustion like in a reciprocating piston engine.
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And if Mazda still use them they must have overcome the mechanical problems otherwise they wouldn't sell any yet other manufacturers have kept clear, I don't understand that unless consumption is still bad and it's not a consideration in the RX8.
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Friend at work has a new RX8. He loves it. It goes like stink, is very well put together, but does about 18 to the gallon, so consumtion is still high.
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Like PU says above, Norton produced a rotary bike that various police forces used in the early/mid 80's, in Derbyshire at least.
They also produced a racing "F1" version (bike not car) that won the British Superbike Championship in 1994 with Ian Simpson on board, (Ron Haslam also rode them). It was also successful at the Isle of Man TT in the early 90's with amongst others, the late Steve Hislop. It was banned from competing after this in the British Superbike event, even though the cc was calculated as 588 against the conventional (in-line and vee) 4 cylinder 750's Japanese bikes. Apparently the ban was not due to the Norton having some sort of capacity/power advantage, (they were very fast bikes and had a fantastic torque characteristic), but was caused by the factory running out of money and so not being able to build enough for sale to the general public (and thus meet Superbike homologation rules). They did produce a limited number for sale to the general public (they were VERY expensive), but they were blighted with cooling problems and I don't think many, if any were actually sold at the time?
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How timely. I have just been moving one of my two Ro80s on the driveway. Both 1974, one a V4 conversion (my "spares" car) the other with a Wankel engine, though not original, it is an early two plug car which has been overhauled by Hurley Engineering (they pioneered the Ro80 V4 conversions).
It really is a shame they couldn't sort out the fuel consumption (I get about 25mpg on a run) because there is nothing quite like a rotary engine in terms of smoothness. The Ro80 was ahead of its time in many ways, engine aside, in 1969 design wise it was way ahead of the competition (I still think if you stuck rubber bumpers on one it would pass for a 1980s car). They all have all round disc brakes, inboard front discs, fantastic direct power steering and a very reliable and easy to use clutchless semi-auto 3 speed gearbox.
I consider mine a long term investment - maybe I'll work out a way to shoehorn an RX8 engine in there one day....(I should add that although my engine is not at full compression it will still happily cruise at 100mph - not bad for a very untuned, 34 year old car)
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I never appreciated the RO80 in the Seventies, but just had a look at a few on Google Images and yes, in design well ahead, about twenty years.
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Nick - thaks for the memory, I watched these races in Donnington !
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Diesel Wankel hier: www.der-wankelmotor.de/Motoren/Rolls-Royce/rolls-r...l
Quite a few aircraft with more conventional Wankel engines. Many derived from Mazda - motoring connection:)
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How I remember the Ro80. My father had five at one point in his company. One was for spares and he had two (one after the other) and the other two were staff cars. They were reliable after a while, although he sent his in house mechanic on the NSU training course to save money!
I would love one now. The interior space was also something to behold. I remember being able to stand suitcases up in the boot, not lie them flat like you have to do in almost all cars today, and especially those with traditional boots.
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Espada- you are right about the boot -due largely to the fact the spare wheel sits to the offisde upright rather than under the boot floor. There is also a real feel of space in the cabin (at least upfront) largely due to the "empty" floor area between passenger and driver footwells.
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290217807278
On e-bay as we speak - I dare you !
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I thought one of the big problems with the RO80 was the semi-auto gear change, with the "magic" clutch that disengaged when you put your hand on the gear knob .... of course most drivers rest their hand on the gear knob for long periods = sky-high rpm and early bath for clutch etc?
Or is that an urban myth?
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Or is that an urban myth?
You'd have to be fairly incompetent to harm one like that. But I can say that that gearchange - only a wide-spaced three-speeder too - took a bit of getting used to. A question of rhythms, like a DS Citroen, but also of remembering that the small pedal on the left is a brake not clutch pedal...
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I looked into buying one a few years ago (before coming back to my senses). I don't recall the clutch being mentioned as a particular problem. There was a problem with the torque converter destroying itself on earlier ones if the engine is persistently revved. I found it baffling that the Ro80 had a clutch and a torque converter.
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Funnily enough the guy I bought my Ro80 from said he had sold one the previous year to a guy and ended up buying it back - he couldn't get used to moving the gearlever without pressing the "clutch" which of course was the brake pedal!
I can't see the problem if you've driven an automatic - the pedals are laid out in exactly the same way with a wide brake pedal. You do need to lift off the gas to change smoothly, and effect the change relatively slowly. Also just to thwart you further, 1st is at the position of 2nd on a "conventional" manual box, 2nd at 3rd position, 3rd at fourth position. Reverse lies where 1st would be, with "P" where reverse would be on a modern VW. Furthermore, this is not marked on the gearlever - I have to "educate" my MOT station each year.
Fortunately, it is not possible to put the car accidentally into reverse as you have to engage first to move into reverse.
The more I write about it, the more strange it seems....
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No, a real automatic is no problem, just two pedals, put the lever in drive, go and stop with the right foot. The problem with the RO80 (and the one or two other cars with similar or analogous systems, like the DS with pneumatic gearchange,) was that you had to move the lever to change gear. This would be OK if you owned such a car and had time to get used to it, but when driving in traffic in one for the first time it was all too easy to revert to habitual hand and foot movements and have an embarrassing moment. As I did when an African friend let me go round a few blocks in his RO80. Mortifying. The DS was a bit easier because its gear lever was just a spindly switch behind the steering wheel. Meant you were less likely to stomp on the brake pedal with your left foot in an unguarded moment. Especially as the DS's brake pedal was identical to the dipswith in a lot of English cars at the time, a little button on the floor.
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Interesting stuff, thanks.
A friend of mine bought an RX7 Turbo II (the late 80s / early 90s 944 lookalike) in '92 as a Mazda approved used ... good job he had a warranty as it ate the original engine, and the factory replacement, in under a year.
Both times the trochoid chamber was scored, not sure why. Explanations varied from poor quality fuel (some things never change!) to excessive town / low speed driving causing carbon build-up .... the upshot was he rejected the car when the second engine failed and came to a severance deal with the dealer.
I've heard that they're a bit like 2-stroke engines, work 'em hard and they're fine!
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The British people has the brain power to discover the universal gravitation principle (It is widely known that to see something right in front of your nose takes a lot of effort --- and intelligence, I will add.) and to proposal the evolution theory.
The British people are also intelligent enough to finally realize that the perpetual-motion machine is nothing but a dream.
It only takes some "engineering feeling" and the fundamental math skill to see the fact that the Wankel engine is a 100% pure "dream" machine. I don't know why it is so hard for the famous British head to get it.
The needed fundamental math skill is nothing but the Calculus courses that all the engineering school students must take when they were fresh men/women of 18- years old. By the way, the Calculus was also established by a British man named Newton.
With the knowledge of Calculus and basic analytic geometry, an engineer shall have no problem to perceive the idea that any two contours of different curve ratio, putting together against each other, will be tangent with each other at exactly one single "point". Here we are talking about mathmatical point --- that means it has the attribute of "location" only; Size? It is not a matter --- at least when the issue is a mathmatical "point".
Here is a simple example: 2 circles of different radii (that is, different curve ratio), leaning agaginst each other, be it internally or externally, will be tangent with each other at exact 1 mathmatical point.
In the Wankel engine, the profile of the rotor's apex seal and the funny-looking curve of the combustion chamber internal surface are no way to be of the same "curve ratio".
Therefore, at any single instant during the normal rotary operation, the apex seal will be "tangent" with the internal surface of the combustion chamber at exact 1 single "mathmatical point".
Considering about the "depth dimension", one may say that the apex seal and the internal surface of the chamber are touching with each other at 1 mathmatical "line". And be aware of that the mathmatical line does have attribute of "direction", but no "thickness" attribute. It is true that the touching line won't be located at the same spot of either the internal surface or the apex seal outline during engine operation, but it is always a line of no thickness no matter what.
Guess what? A line of "no thickness" happens to have a nick-name called "sharp edge", which is composed of very few amount of atoms. Hence, this mathmatical line is very weak, and will be worn-out very soon.
"What if it is not weak? It is thin and sharp line, but it is tough nevertheless because the contribution of the NEW TECHNOLOLY."
What will a die-hard sharp edge do when something else pushing against on it? Cut, scrape, or both, right? So, if the apex seal is tougher, the chamber surface get damaged, and vice versa.
"Then, will the apex seals and the internal surface of the chamber finally get used to each other and break-in after they have seriously hurt each for a while?"
Analytic Geometry says NO as long as they are contours of different curve ratio. You don't need to be a PhD in mathmatics to see that there is no way for the contour of the apex seals and internal surface to be of the same curve ratio no matter how they are grinding/scrapping each other for how long.
Therefore, they will always touch each other at one mathmatical line of no thickness. Consequently, they will keep on damaging each other fiercely until the leak is so severe that there is no vocuum, no compression, and the engine won't work any more.
"Hey, good news. The NEW TECHNOLOGY is magic, it can make both the apex seals and the internal surface not only extremely strong but also equally strong. So, no one can hurt the other any more."
This sounds really like a dream now.
The comprssion room, exhausting room and the combustion room of the engine are separated with each other by 1 mathmatical line of "no thickness". That's the fact of this Wankel "dream" machine.
And the fuel used is pertroleum gas: after burning, the residual materials are composed of water, carbon dioxide and sulfide base acid. None of these material will treat our mathmatical line nicely. Will the magic technology additionally prevent the tough line from being rustty by harmful pertroleum residual?
Mercede sees that, GM sees that, Toyota, Honda and all the other car makers see that. Only Mazda does not see that and pours millions and millions dollars on the Wankel engine. I doubt that Mazda have ever earned a single penny by making RX car.
In my honesty opioion, all the Mazda's engineers who get involved the Wankel engine project need to go back to school to take the basic Calculus and Analytic Geometry again.
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"the Wankel engine is a 100% pure "dream" machine."
Which is probably why I want an RX-8! As for not making money from it, Mazda has been making them successfully since 1970 (the RX-2) so it should be pretty well sorted by now, with or without the dodgy maths.
WRT the RO80, I'm pleased to hear that there are few still running. IIRC, it was Car Magazine's 'car of the decade' in 1979 (possibly the only one they ever had). They still look modern, IMO.
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A fair point lengthily made, bystander. There are other problems for the apex seals in the Wankel engine too.
At certain points in the engine's cycle, the tip seals have to leave the epitrochoid bore in order to allow the passage of either incoming charge or spent exhaust to the next chamber. The consequence of this is that any lubricant which might have been used to enhance the chances of survival of bystander's "line" is burnt. No good for emissions or wear. Replacing lubricant with soot (on the exhaust cycle) is not clever.
A cylindrical bore with compression rings and an oil control ring is actually a very elegant solution to the problem of separating fire from running parts.
I am not a lover of the products or (any more) a customer of the Ford Motor Company. I give them full credit however for not spending a cent on the development of this engine whilst GM, Rolls Royce, Daimler-Benz, Norton(!) and several others were pouring money into it. I remember the then head of Ford saying that this design would not receive any development money whilst he was in charge.
I think on that occasion, unusually for the head of an American Corporation, he had a real understanding of the issues.
659.
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Didn't stop the RX-8 engine becoming the 'International Engine of the Year' in 2003, however. Tip seals notwithstanding, the rotary engine looks a pretty elegant solution to me, with its lack of reciprocating parts, cambelts/chains and clattery valvegear (which also needs its own seals).
BTW, I thought Mazda and Ford were partners, so they may have spent a few cents on it, however inadvertently...
Edited by J Bonington Jagworth on 12/04/2008 at 13:40
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Anything awarded "of the year" status does not have to withstand the acid test of real life ownership. Armchair journalism is easy - engineering isn't.
The Wankel engine swaps one smallish problem for a whole bunch of big ones. Out of balance forces due to reciprocation can be fully balanced in a piston engine by choosing the optimum configuration (straight 6 or compounds thereof). It can be reasonably balanced by using a more compact and cheaper package (straight 4 with Lanchester shafts). The rotor of a Wankel engine describes an eccentric path around the output shaft - so it's not balanced either. This is why multiple rotors are necessary. So there is not much of a "simplification" over a conventional engine.
The real crunch comes when you ask the obvious questions. To a completely non-mechanically minded owner of a vehicle with an internal combustion engine, ask him what he most dislikes about the engine.
Vibration will hardly ever figure in a competently designed and applied piston engine, as most are. Fuel consumption, pollution and cost of maintenance coupled with long term reliability will be the important issues to him.
RIP Wankel. (nearly put the "van" in).
659.
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One of the (many, IMO) nice things about the Wankel engine is that it rarely fails catastrophically. A broken con-rod or cambelt (I've experienced both) in a conventional engine will bring it to an immediate halt and may even require a bit of nifty declutching to keep the wheels turning. The simplicity of the design is its greatest virtue, and helps keep it small and light. The lack of vibration is not something you necessarily appreciate until you've experienced it - have you driven one?
Single-rotor motorcycle engines (Norton and Suzuki) were both pretty smooth and are also used in light aircraft...
Edited by J Bonington Jagworth on 12/04/2008 at 15:00
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"To a completely non-mechanically minded owner..."
Me: "What do you most dislike about the internal combustion engine?"
Completely non-mechanically minded owner: "Wozzat then?"
:-)
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>not much of a "simplification" over a conventional engine.
Hmm. Let's see. If Mr Otto and his friends had invented the Wankel engine first and after 100 years of development, someone had come along with the brilliant idea of replacing a motor with three moving parts with a larger and heavier one with reciprocating pistons and con-rods, a hefty crankshaft, a cam or two and the means to rotate them (failure of which would wreck the engine), anything up to 32 spring-loaded valves and concomitant intake and exhaust plumbing, he would be laughed off the stage!
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Ford own more than 30% of Mazda which under Japanese law makes them the owner of the company.
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Didn't the Talbot Solara become European Car of the Year? Sales in the UK did eventually reach DOUBLE figures.One of the problems with the Wankel is how to work out it's capacity.It is either a very large engine-not particularly efficient-or a very small engine that uses vast amounts of fuel compared with other engines of similar capacity.
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Wasn't the Ro80 spectacularly expensive when it was first sold in the UK? (as I believe were other German marques?) Hence it's potential market was limited to the informed and wealthy customer (of which there aren't many). I believe it was of the order of 30-40% more than a decent 6 cylinder Jaguar at the time.
Can anyone of sufficient years explain why the posher German cars were so pricey in the late 60s and early 70s - was it just an exchange rate?
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Doesn't it make an, erm, interesting sound when unsilenced.
I remember a report on the Le Mans Mazda saying it sounded like a donkey braying, and was the loudest in the pit lane. The other mechanics used to applaud when it was switched off!
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Doesn't it make an erm interesting sound when unsilenced.
I saw one on the drag strip at Santa Pod once, and it sounded like an extremely loud electric wood planer, planing wood.
A bloke with a late model RX7, took the Wankel engine out and fitted a Chevy LS1 V8, giving far more power and torque, similar fuel consumption, less maintenance required, and it sounds nothing like a wood planer..
;o)
Edited by Rich 9-3 on 12/04/2008 at 20:12
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"giving far more power and torque"
Not to mention weight.. :-)
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Oh yeah, it's as thirsty as an average V8...
Check out my RX-8 home-made movie at the bottom of this page:
www.autogaleria.pl/auto_test/test.php?id=112
Plus something about its build quality and a "vacuum cleaner" engine sound:
vincentus.wrzuta.pl/film/3DDZvVn4ny/
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Remove that posh "Renesis" engine cover and the whole thing looks somewhat motorcycle-ish:
www.fotosik.pl/pokaz_obrazek/pelny/91b87a032a08d6e...l
Japanese bits & pieces, including something from Mitsubishi, only 40-cm long oil dipstick and four-nozzled screenwash thingy - just like the one in an Unimog, the famous offroader :)
www.fotosik.pl/pokaz_obrazek/pelny/0a7e638f3089bbb...l
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"giving far more power and torque" Not to mention weight.. :-)
According to the mag article I have, the weight difference is not big enough to spoil the handling. An LS1 is all-aluminium with a plastic intake manifold, so not as heavy as you would think.
But its a controversial subject among US RX owners!:
www.rx7club.com/archive/index.php/t-255423.html
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They sound absolutely gorgeous, as this clip of a Norton rotary racer demonstrates:
www.youtube.com/watch?v=g6iSSAIXlGc&feature=related
Don't forget the Felix Wankel himself disowned the car manufacturers' developments of his patents, saying they had turned his "race horse" into a cart horse. In his original designs and prototypes, the rotor housing also rotated around the rotating rotor (at 1/3 speed IIRC).
This gave exception power and torque but caused certain basic problems such as having to strip the motor to change spark plugs.
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"race horse"
It would be far more common as a racing engine if the FIA and others could agree how to classify it. I note that when Mazda won Le Mans in 1991 with their 4-rotor 787, rotary engines were promptly banned! So sporting...
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>>One of the problems with the Wankel is how to work out it's capacity.It is either a very large engine-not particularly efficient-or a very small engine that uses vast amounts of fuel compared with other engines of similar capacity.
I tend to agree with jc2's view. Whichever you look at it, it's not great.
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why do you need to bother to work out engine capacity? Surely, the engine's consumption, output and weight are more important?
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"A fair point lengthily made"
Thank you.
There is huge room for my english skill to be improved, that's obvious.
Comparing to those Wankel enthusiasts who have spent more than half a century to get the Wankel run, however, my comment might be not concise, relatively it was not lengthy at all.
Wankel engine is kind of like a clumsy skatter who insists on skating in the direction traversing to his skatting blades. And the Mazda engineer team is the never-give-up coach, who has devoted himself for 40+ years to make this "crab-walking" style skatter run.
"A cylindrical bore with compression rings and an oil control ring is actually a very elegant solution to the problem of separating fire from running parts."
Those rings touch the cylindrical bore in a circular band to which I would name as "engineering line".
Unlike the "mathematical line", the "engineering line" does come with "thickness". That's a very important factor which could be easily ignored.
Because the piston rings and the the cylindrical bore are all of the same diameter cicular shapes, they all are of the same ratio of curve. That makes the rings and the bore surface touching each other in a complete circle band area (which also makes it an "engineering line"), not just at a few size-less points. And it always comes with more than one piston rings; that is, the touching area is multiplied.
See, the pressure (P) is the ratio of Force (F) over interfacing Area (A). That is: P = F/A.
The combustion force (F) inside the enginge is so huge as to be able not just move but accelerate tons of mass.
A "mathmatical line" is of no thickness, which makes the touching area (A) approaching infinitesimal. Hence, the pressure that the touching portion must endure (P) will be infinitely large.
Facing to this infinitely high pressure, the parts, regardless how they have been strenthened, are doomed to fatigue very soon around the touching area.
That is the terrible torture that a cylindrical engine never need to be suffered from.
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craig-pd130 wrote:
?A friend of mine bought an RX7 Turbo II (the late 80s / early 90s 944 lookalike) in '92 as a Mazda approved used ... good job he had a warranty as it ate the original engine, and the factory replacement, in under a year.?
Replacing 2 engines within 1 year? That?s much too often than the frequency people change the spark plugs for their cylindrical engine vehicles. Most non-rotary engine cars actually never change engine at all.
J Bonington Jagworth wrote:
?WRT the RO80, I'm pleased to hear that there are few still running.?
It won?t get any attention by any cylindrical engine car which has done 300K+ miles and still runs. I happen to have a 1988 Acura Integra. After offering service of 260K+ miles, it still makes 32.8 miles per gallon in freeway.
You can pretty much stand in any crossing streets to randomly stop a Honda, Toyota or Mazda non-rotary "seniority car" and find that its mileage meter read higher than 200K miles.
Contrastively, it would take the same amount of head-bounty for Bin Laden as to get a Mazda RX which has made 200K+ miles without ever changing engine. Even with the same reward, it will be harder to get such an RX car than to get Bin Laden. Bin Laden, like him or not, is at least really exist in this world. RX car? As I said, is a 100% pure dream car.
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In 1991 Mazda's 787b model came first in the 24h Le Mans race using a w***el engine. During the past years, Mazda took part in many races across Europe manufacturing cars that used w***el engines, until finally got the prize in 1991. As soon as possible, Audi and some other manufacturers protested against the w***el engine that only Mazda used and the authorities banned the w***el engine for the following years. They managed to get Mazda out of the Le Mans racing. It is widely known that during a Le Mans race racing cars are reaching their full potential and despite the fact that they have to go fast enough, their main task is to remain in the race track as much as they can which means that as fewer mechanical problems so much more possibilities to reamin in the top ranking. How a w***el engine withstood the problems you mentioned and finally took the prize??? It was the other drivers' or manufacturers' fault that Mazda came first??? How did they manage to keep the apex seals and the internal surface of the chamber strong enough not only to endure such a race but to win it afterall???
What about airplane w***el engines?
What about bike w***el engines?(Norton)
What about citroen's w***el engines?(GS or GZ birotor which are still working fine today after 35 years?)
I would like to give me a full answer about the w***el engine itself,from the day it was produced till nowadays.(the new technology)
I would also like to get an opinon from thermodynamic point of view.
Thank you for reading my message!!!
Have a good day!
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